Two-stroke engine



Jan. 13. 1925,

F. DELLA-FERRERA TWO-STROKE ENGINE Filed Nov. 22, 1923 Patented Jan. 13, 1925.

UNITED STATES PATENT OFFICE.

TWO STROKE ENGINE.

Application filed November 22, 1923. Serial No. 676,346.

To all whom it may concern:

Be it known that I,FEDERIGO DELLA-FER- RERA, a subject of the King of Italy, and resident of Turin, in the. Kingdom of Italy, have invented certain new and useful Improvements in Two-Stroke Engines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable ot ers skilledin the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification. 1

This invention relates to improvements in two-stroke engines, having their cylinders arranged in pairs with a common explosion chamber. According to the invention the cylinders of each pair :are arranged across each other sothat the axis'of the piston pins at theend of the compression stroke meet simultaneously the; line interesecting the planes passing through the axisof the cylinders and parallel to the axis of the driving shaft. Therefore the pistons connected with the same crank pin go simultaneously or nearly so through the upper dead point, and with a considerable interval (according to the'divergence of the cylinders) through the lower dead point. I

It is thus possible to open the outlet ports of one of the cylinders some time before the inlet or scavenging ports of the other cylinder, and to close simultaneously all the ports or to close later the inlet ports according to their relative height, so that at the explosion the pistons are practically inthe same position. a

This arrangement obviates the drawbacks of the engines with inverted V like inclined cylinders, connected together, or with cylinders out of phase with respect to the driving shaft. These drawbacks are due mainly to the fact that at the explosion at least one of the pistons is always in an unfavourable position for receiving the explosion pressure.

The accompanying drawing shows the engine forming the object of this invention.

Figure 1 shows the relative osition of the pistons at the moment when t ey begin uncovering the inlet ports.

Figure 2vis a similiar view at the moment, when the inlet ports are closed.

Figure 3 shows the two pistons going simultaneously through the upper dead point.

Figure 4 is a longitudinal section showing the invention used in connection with fourcylinder engines.

Figure 5 is a cross section on line AB of Figure 4.

Figure 6 is a section on line C, D of 'Fi ure 4..

n the drawing, 1 and 2 are the cylinders,

having their axes m, y; :23, z displaced positively and negatively, respectively, to the axis :12, w of the driving shaft, so that their projections form an angle with the vertex :1; turned upwards.

The point x is placed at the highest position of the piston pins 3, 4, so that at the upper dead point the pistons 5, 6 meet at the same height, while at the lower dead point they are more or less apart from each other, according to the smaller or larger aperture of the angle y, m, a. On the drawing, the angle is of about 15 so that the inlet ports 7 open (Figure 1) when the outlet ports 8 are already half open, although the ports 8 are only about one third higher than the inlet ports 7.

The closure of the inlet ports 7 takes place just a short time before the closure of the outlet ports 8 (Fig. 2) and it is sufficient to increase slightly the degree of the angle 3 m, z, in order to obtain the simultaneous or even retarded closure. The pistons always attain the dead point simultaneously with any angle, provided the vertex corresponds to the highest position of the piston to pin.

Similar results may be obtained by increasing the displacement of one cylinder and decreasing the displacement of the other down to zero, as it is exactly the relative displacement of the cylinders that determines the form of the kinematic diagram.

Figures 4, 5 and 6 show the invention used in connection with a four-cylinder, water cooled engine for motor vehicles.

The engine consists of a crank case in three parts 20, 21, 22 forming two tight closed chambers, enclosing the crank shaft consisting of six flywheels 23 connected by the crank shaft 24 and crank pins 25, against which abut the rods 26 of the pistons 32, 32 32", 32

To the crank case are secured the cylinders 27, 27 27 27 cast in two-cylinder blocks and with 'water jacket 28, which wholly hides the cylinder inclination, so that the engine-has the outer appearance of a normal engine with four cylinders in alignment;

The cylinders 27 27 are provided with suction ports 29, connecting the two chambers of the crank case with the carburetter, and with outlet ports 30.

The cylinders 27, 27 are provided. with scavenging ports 31 conveying the mixture compressed in the crank case to the cylinders.

The engine difi'ers from known engines in that there'tarded opening of the inlet or scavengingports relatively to the outlet ports depends, irrespective of the relative location of the ports, upon the relative in- I clinations of the cylinders which retards the closure and makes it later than would, be possible by the difi'erence of height of the inletports. The earlier openin of the outlet ports due to angularity of t e cylinders can be reduced to zero or the opening even made later, assuming the difference in height between the outlet and inlet ports is very small or there is no difference at all, when the distance between the cylinders at their lower ends is considerable.

Identical results maybe obtained by increasing the inclination of one of the cylinders and diminishing that oi the other cylinder until it requires a radial position, provided the line intersecting the planes passing through the axis of the cylinders and parallel to the axis of the engine shaft,

has such a position that the axes of the piston pins simultaneously meet this line where the pistons reach their upper dead point. I

This arran ement allows of a better filling of the cy inder and prevents the gases from flowing out throu h the outlet ports by kinetic energy when e scavenging ports are still closed and producing a pressure lower than the atmos heric pressure in the mixture contained in t e cylinder.

What'I claim is:

1. A two-stroke engine comprising a pair of c linders inclined with respect to one anot er having inlet and outlet ports and communicating at one end with a common combustion chamber, pistons in the cylinderscontrolling the ports, a single crank having its axis in a plane passing through the vertex of the angle formed between the axes of the cylinders and means for operatively tex of-thev angle formed between the-axes ofthe cylinders, rods pivotedly connected to the crank, plIlS connecting the rods to the pistons, the axes of-the pins being arranged to simultaneously reach thevertex. of said angle whereby the pistons reach the upper dead point simultaneously, while at the lower dead point the-piston operating the outlet port is in advance of the piston operating. the suction portr 1 3. A two-stroke engine comprising a pair of cylinders, inclined with res ect to one another, one of which has an in ct port and the other an outletport and communicating at one end. with a' common combustion chamber, pistons in the cylinders controlling the ports, a driving shaft having a single crank arm andhavin'g its axisinraplane passing through the vertex "of the angle formedbetween the axes of the cylinders, and rods connecting to the crank arm to the pistons at points adapted to simultaneously reach the vertex-of" said angle on the up-stroke, whereby the pistonsreach the upper dead point simultaneously.

4:. In a two-stroke engine, a driving shaft having a single crank, a cylinder arranged radially to the driving shaft, a second cylinder inclined with respect to the first cylinder, one of the cylinders having an inletort and the other an outlet port, a comustion chamber communicating with both cylinders, pistons in the cylinders controlling the ports, and rods connecting the crank to the pistons at points adapted on the upstroke of the pistons to simultaneously reach the vertex of the angle formed be tween the axes of the cylinders whereby the pistons reach the upper dead point simultaneousl I In testimony that I claim the foregoing as my invention, I have signed in name.

FEDERIGO DELLA-FE RERA. 

